• Free to download and use
• Loads of new features over 4.1 version.
• Excellent support for a range of platforms.
• Performs well in small and medium applications.
• Most popular Open Source database engine.
• Supports advanced concepts such as replication.
• Performs extremely well in the average case.
Room for Improvement:
• It doesn't support stored procedures.
• You probably wouldn't use it for heavy-duty installation.
• There is no active directory for integration with Microsoft SQL Server or other data bases.
As a developer I have used many database engines but MySQL is by far the best known and most popular Open Source database engine.